I'm impressed that you can do this after only a few weeks. My daughter plays clarinets, and I remember it took a while for the kids to get a decent sound out of it, much less an actual song. I would recommend getting an instructor to at least make sure your embouchure is correct so the notes come out without that "stuffiness", and to also teach you about the difference between reeds and mouthpieces, unless you've already done all that, of course. That same daughter also worked for (and still occasionally still works for when she has time) a pro clarinet player who also ended up making his own mouthpieces, and now has a business selling student and pro barrels and mouthpieces for clarinets, so she's also learning the technical aspects of the instruments.